Minato has enjoyed a reasonably happy marriage for 15 years despite never having children. Her life changes completely when her father-in-law Akira's dementia worsens and she becomes consumed by his care. He sometimes mistakes her for his late wife and makes sexual advances. Minato finally lashes out, but Akira interprets even her anger as his wife's bad mood and forces her down. The unexpected sexual stamina of her elderly father-in-law leaves Minato shaken beyond reason...